This invention relates to a subsidiary station for use in a time division multiple access network.
Such a time division multiple access network comprises a central or base station, a terminal station remote from the central station, and at least one repeater station placed between the central station and the terminal station. For convenience of description, each of the terminal and the repeater stations is called a subsidiary station.
When initially set or newly installed in the network, a conventional subsidiary station must be given an internal delay so that a total delay given by adding the internal delay to twice a propagation delay from a next preceding station of the network to the subsidiary station should be equal to a frame period of a downward signal received from the central station as will later be described. When the subsidiary station receives the downward signal from the central station, the subsidiary station transmits an upward signal towards the central station. When at least one preceding repeater station is placed between the central station and the subsidiary station, the upward signal reaches the central station a lapse of a time duration, given by multiplying the frame period by the number of the preceding repeater station, after transmission of the downward signal from the central station. Thus, a long time is wasted until reception of the upward signal at the central station after transmission of the downward signal from the central station.
A repeater station is disclosed in U.S. Pat. No. 4,490,818 issued to Shigeru Otsuka and assigned to NEC Corporation. The repeater station is also disclosed in Canadian Patent No. 1,191,205 and in Australian Patent No. 553,157. The repeater station may have a predetermined initial delay shorter than the frame period. It is therefore possible to shorten the time duration between transmission of the downward signal from the central station and reception of the upward signal at the central station. However, the repeater station is incapable of automatically deciding the internal delay.